59 lines · cpp
1//===--- Stack.cpp - Utilities for dealing with stack space ---------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8///9/// \file10/// Defines utilities for dealing with stack allocation and stack space.11///12//===----------------------------------------------------------------------===//13 14#include "clang/Basic/Stack.h"15#include "llvm/Support/CrashRecoveryContext.h"16#include "llvm/Support/ProgramStack.h"17 18static LLVM_THREAD_LOCAL uintptr_t BottomOfStack = 0;19 20void clang::noteBottomOfStack(bool ForceSet) {21 if (!BottomOfStack || ForceSet)22 BottomOfStack = llvm::getStackPointer();23}24 25bool clang::isStackNearlyExhausted() {26 // We consider 256 KiB to be sufficient for any code that runs between checks27 // for stack size.28 constexpr size_t SufficientStack = 256 << 10;29 30 // If we don't know where the bottom of the stack is, hope for the best.31 if (!BottomOfStack)32 return false;33 34 intptr_t StackDiff =35 (intptr_t)llvm::getStackPointer() - (intptr_t)BottomOfStack;36 size_t StackUsage = (size_t)std::abs(StackDiff);37 38 // If the stack pointer has a surprising value, we do not understand this39 // stack usage scheme. (Perhaps the target allocates new stack regions on40 // demand for us.) Don't try to guess what's going on.41 if (StackUsage > DesiredStackSize)42 return false;43 44 return StackUsage >= DesiredStackSize - SufficientStack;45}46 47void clang::runWithSufficientStackSpaceSlow(llvm::function_ref<void()> Diag,48 llvm::function_ref<void()> Fn) {49 llvm::CrashRecoveryContext CRC;50 // Preserve the BottomOfStack in case RunSafelyOnNewStack uses split stacks.51 uintptr_t PrevBottom = BottomOfStack;52 CRC.RunSafelyOnNewStack([&] {53 noteBottomOfStack(true);54 Diag();55 Fn();56 }, DesiredStackSize);57 BottomOfStack = PrevBottom;58}59